Autodesk: Set Default Path of TBB and OpenSubdiv in pxrConfig.cmake.in

[erikaharrison-adsk]

Description of Change(s)

Similar to MaterialX exported targets, adding these default paths makes pxrConfig.cmake easy to use, especially when TBB and OpenSubdiv are passed to USD cmake step. And user doesn't need to specify TBB_DIR and OpenSubdiv_DIR when using pxr exported targets.

Link to proposal (if applicable)

• N/A

Fixes Issue(s)

• N/A

Checklist

• I have created this PR based on the dev branch

• I have followed the coding conventions

• I have added unit tests that exercise this functionality (Reference:
  testing guidelines)

• I have verified that all unit tests pass with the proposed changes

• I have submitted a signed Contributor License Agreement (Reference:
  Contributor License Agreement instructions)

[pmolodo]

I tested this with build_usd.py, and with the default values (ie, --no-onetbb), I got a pxrConfig.cmake with:

if (NOT DEFINED PXR_FIND_TBB_IN_CONFIG)
    set(PXR_FIND_TBB_IN_CONFIG "OFF")
endif()
if (PXR_FIND_TBB_IN_CONFIG)
    # Set TBB_DIR to where the TBBConfig.cmake file was located.
    # This can be overridden by specifying a different TBB_DIR when running cmake.
    if (NOT DEFINED TBB_DIR)
        if (NOT [[TBB_DIR-NOTFOUND]] STREQUAL "")
            set(TBB_DIR [[TBB_DIR-NOTFOUND]])
        endif()
    endif()
    find_dependency(TBB 2020.3 CONFIG)
endif()

I'm unsure of Cmake's behavior if ${TBB_DIR} STREQUAL "TBB_DIR-NOTFOUND" - if this causes an immedate fail of find_package(TBB), this could create problems for downstream deps that want to use OneTBB (even though USD didn't use it).
(If find_package(TBB) still checks all the "standard places," even if ${TBB_DIR} STREQUAL "TBB_DIR-NOTFOUND", though, then this should be harmless.)

If I built with build_usd.py --onetbb, I got:

if (NOT DEFINED PXR_FIND_TBB_IN_CONFIG)
    set(PXR_FIND_TBB_IN_CONFIG "ON")
endif()
if (PXR_FIND_TBB_IN_CONFIG)
    # Set TBB_DIR to where the TBBConfig.cmake file was located.
    # This can be overridden by specifying a different TBB_DIR when running cmake.
    if (NOT DEFINED TBB_DIR)
        if (NOT [[/src/USD/usd_build/USD/_build/Release/usd0.25.05/py3.10/install/lib/cmake/TBB]] STREQUAL "")
            set(TBB_DIR [[/src/USD/usd_build/USD/_build/Release/usd0.25.05/py3.10/install/lib/cmake/TBB]])
        endif()
    endif()
    find_dependency(TBB 2021.9.0 CONFIG)
endif()

...which means we've ended up with a non-portable pxrConfig.cmake file. Is there a way we can check to see if TBB_DIR is underneath the install directory, and if so, set it to, ie, `${_IMPORT_PREFIX}/lib/cmake/TBB"?

I'm actually a bit surprised that, if building with TBBConfig.cmake, cmake's automatic XXXConfig.cmake generation doesn't handle this more gracefully. Is there a way to "tell" cmake that a dependency will be packaged along with the package being built? Or a more standard / cmake-ish way to get portable XXXConfig.cmake files?

[pmolodo]

To be fair this PR - this same issue is also happening with other parts of pxrConfig.cmake, like MaterialX_DIR... and this PR was presumably just following the already established pattern. Unfortunately, this established pattern seems somewhat problematic...

[jesschimein]

Filed as internal issue #USD-10931

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[jesschimein]

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[tallytalwar]

/AzurePipelines run

[tallytalwar]

/AzurePipelines run

[jesschimein]

/AzurePipelines run